Is this a boost or vacum line?

**2k1audiS4** · 09-25-2008 07:13 AM

Everytime I move or touch it to adjust my "T" fitting for my boost guage all I hear is the sound of leeking air. Now I have a boost leak and I am trying to figure out if it might be from this. Let me know if it could be the problem so I can replace it tonight before I head to H2O tomorrow. Other wise I think it is my vacume line that my boost guage is spliced into. If its not a boost or vacum line then what is its purpose. Thanks in advance.

-Rob

**gointoscott** · 09-25-2008 07:50 AM

That is the brake booster. I know that much, I think it will affect boost, but dont know for sure.

Do a search on brake booster and you will find some info on the item. I remember seeing pictures of people replacing them and how uch they paid to replace them.

**mholme** · 09-25-2008 07:51 AM

That's the vacuum line for the brake booster. There are a couple of check valves inline with it as well. I had a leak there too, and yes, it will bleed boost.

**AudiSportB5S4** · 09-25-2008 08:06 AM

OP, I asked the same question to JaybQuick@JHM here on the boards who knows a shitload of stuff about not only the S4 but cars in general. anyways, I asked the same thing because I thought maybe I was losing boost anyways, this is what he told me..

"The check valve is just to keep the vacuum in your brake booster so under boost you don't lose your power brakes. A bad check valve would only hurt the brake booster performance. So if there is a vaccum leak through this, it would be the booster itself. Easy check would be to cap this off and drive around and see if it works. Brakes will take more effort, but it is a free way to check it."

**nizmosx** · 09-25-2008 11:46 AM

Vacuum as others have said its the brake booster hose. very easy to remove if need be,

**CheesmoS4** · 09-25-2008 01:03 PM

can u pour seafoam down that hose, or is there a better vacum line to get into, if so can anyone show which line is the best

**S4_NE** · 09-25-2008 03:29 PM

Originally Posted by 2k1audiS4

Everytime I move or touch it to adjust my "T" fitting for my boost guage all I hear is the sound of leeking air. Now I have a boost leak and I am trying to figure out if it might be from this. Let me know if it could be the problem so I can replace it tonight before I head to H2O tomorrow. Other wise I think it is my vacume line that my boost guage is spliced into. If its not a boost or vacum line then what is its purpose. Thanks in advance.

-Rob

when you car is on if that line is leaking bad you will hear it just sitting there it will sound like a whistle sound hope this helps